Dehydrogenation with a multicomponent catalyst

ABSTRACT

DEHYDROGEATABLE HYDROCARBONS ARE DEHYDROGENATED BY CONTACTING THEM AT DEHYDROGENATION CONDITIONS WITH A CATALYSTIC COMPOSITE COMPRISING A COMBINATION OF CATALYTICALLY EFFECTIVE AMOUNTS OF A PLATINUM GROUP COMPONENT, A NICKEL COMPONENT, A GROUP IVA METALLIC COMPONENT AND AN ALKALI OR ALKALINE EARTH COMPONENT WITH A PORROUS CARRIER MATERIAL. A SPECIFIC EXAMPLE OF THE DISCLOSED DEHYDROGENATION METHOD IS METHOD FOR DEHYDROGENATING A DEHYDROGENATABLE HYDROCARBON COMPRISING CONTACTING THE HYDROCARBON AT DEHYDROGENATION CONDITIONS WITH A CATALYST COMPRISING A COMBINATION OF A PLATINUM COMPONENT, A NICKEL COMPONENT, A GERMANIUM COMPONENT AND AN ALKALI OR ALKALINE EARTH COMPONENT WITH AN ALUMINA CARRIER MATERIAL. THE AMOUNTS OF THE CATALYTICALLY ACTIVE COMPONENTS CONTAINED IN THIS LAST COMPOSITE ARE, ON AN ELEMENTAL BASIS, 0.01 TO 5 WT. PERCENT PLATINUM, 0.01 TO 5 WT. PERCENT NICKEL, 0.01 TO 5 WT. PERCENT GERMANIUM AND 0.1 TO 5 WT. PERCENT OF THE ALKALI OR ALKALINE EARTH METAL.

United States Patent DEHYDROGENATION WITH A MULTI- COMPONENT CATALYST Frederick C.Wilhelm, Arlington Heights, 111., assignor to .*--'Universal Oil Products Company, Des Plaines, Ill. No. Drawing. Application Oct. 16, 1970, Ser. No. 81,512, ";.-,wh ich is a continuation-impart of application Ser. No. 15,960,. Mar. 2, 1970, both now abandoned. Divided ',,and this application Nov. 3, 1972, Ser. No. 303,470

M Int. Cl. C07c /24 US. Cl. 260-668 D 23 Claims ABSTRACT THE DISCLOSURE 'Dehydrogenatable hydrocarbons are dehydrogenated by contacting them at dehydrogenation conditions with a catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a 'nickel component, aGroup IVA metallic component and an alkali or alkaline earth component with a porous carrier material. A specific example of the disclosed dehydrogenation method is a method for dehydrogenating a dehydrogenatable hydrocarbon comprising contacting the hydrocarbon at dehydrogenation conditions with a catalyst' comprising a combination of a platinum component, a nickel component, a germanium component and an alkali'or alkaline earth component with an alumina carrier material. The amounts of the catalytically active components contained in this last composite are, on an elemental basis, 0.01 to'2 wt. percent platinum, 0.01 to 5 wt. percent nickel, 0.01 to' 5 wt. percent germanium and 0.1 to 5 wt. percent of the alkali or alkaline earth metal.

' CROSS-REFERENCES TO RELATED APPLICATIONS This'application is a division of my prior, copending and now abandoned application Ser. No. 81,512, filed on Oct. 16,1970, which in turn is a continuation-in-part of my prior, copending and now abandoned application entitled Catalytic Composite of Platinum, Nickel and a Group --IVA Metal With Carrier Material and Uses Thereof'filed Mar. 2, 1970 and assigned Ser. No. 15,960.

DISCLOSURE The subject of the present invention is, broadly, an improved methodfor dehydrogenating a dehydrogenatable hydrocarbon to produce a product hydrocarbon containing the same number of carbon atoms but fewer hydrogen atoms. In a narrower aspect, the present invention is a method of dehydrogenating normal paraffin hydrocarbons containing 4- to 30 carbon atoms per molecule to the corresponding normal mono-olefins with minimum production of side products. Another aspect of the present-invention involves a novel catalytic composite comprising a combination of catalytically effective amounts ofia -platinum group component, a nickel component, a GroupiIVA metallic component, and an alkali or alkaline earth component with a porous carrier material. This composite has highly preferred characteristics of activity, selectivity, and stability when it is employed in the delryth-ogenation of dehydrogenatable hydrocarbons such as aliphatichydrocarbons, naphthenic hydrocarbons and alkylaromatichydrocarbons.

The dehydrogenation of dehydrogenatable hydrocarbons is an important commercial process because of the great and expanding demand for dehydrogenated hydrocarbons for use in the manufacture of various chemical products such as detergents,plastics, synthetic rubbers, pharmaceuticalproducts, high octane gasoline, perfumes, drying oils, ion-exchange resins, and various other products well known to those skilled in the art. One example ice of this demand is in the manufacture of high octane gasoline by using C and C mono-olefins to alkylate isobutane. A second example is the greatly increased requirements of the petrochemical industry for the production of aromatic hydrocarbons from the naphthene component of petroleum. Another example of this demand is in the area of dehydrogenation of normal parafiin hydrocarbons to produce normal mono-olefins having 4 to 30 carbon atoms per molecule. These normal mono-olefins can, in turn, be utilized in the synthesis of vast numbers of other chemical products. For example, derivatives of normal mono-olefins have become of substantial importance to the detergent industry where they are utilized to alkylate an alkylatable aromatic such as benzene, with subsequent transformation of the product arylalkane into a wide variety of biodegradable detergents such as the alkylaryl sulfonate type of detergent which is most widely used today for household, industrial, and commercial purposes. Still another large class of detergents produced from these normal mono-olefins are the oxyalkylated phenol derivatives in which the alkyl phenol base is prepared by the alkylation of phenol with these normal mono-olefins. Yet another type of detergent produced from these normal mono-olefins is a biodegradable alkylsulfate formed by the direct sulfation of the normal mono-olefin. Likewise, the olefin can be subjected to direct sulfonation to make biodegradable alkenylsulfonates. As a further example, these mono-olefins can be hydrated to produce alcohols which then, in turn, can be used to produce plasticizers, synthetic lube oils and the like products.

Regarding the use of products made by the dehydrogenation of alkylaromatic hydrocarbons, these find wide application in industries including the petroleum, petrochemical, pharmaceutical, detergent, plastic industries, and the like. For example, ethylbenzene is dehydrogenated to produce styrene which is utilized in the manufacture of polystyrene plastics, styrene-butadiene rubber, and the like products. Isopropylbenzene is dehydrogenated to form alphamethyl styrene which, in turn, is extensively used in polymer formation and in the manufacture of drying oils, ion-exchange resins and the like material.

Responsive to this demand for these dehydrogenation products, the art has developed a number of alternative methods to produce them in commercial quantities. One method that is widely utilized involves the selective dehydrogenation of dehydrogenatable hydrocarbons by contacting the hydrocarbons with a suitable catalyst at dehydrogenation conditions. As is the case with most catalytic procedures, the principal measure of effectiveness for this dehydrogenation method involves the ability to perform its intended function with minimum interference of side reactions for extended periods of time. The analytical terms used in the art to broadly measure how well a particular catalyst performs its intended function in a particular hydrocarbon conversion reaction are activity, selectivity, and stability, and for purposes of discussion here these terms are generally defined fora given reactant as follows: (1) activity is a measure of the catalysts ability to convert the hydrocarbon reactant into products at a specified severity level where severity level means the conditions used that is, the temperature, pressure, contact time, and presence of diluents such as H (2) selectivity usually refers to the amount of desired product or products obtained relative to the amount of the reactant charged or converted; (3) stability' refers to the rate of change with time of the activity .and selectivity parameters obviously the smaller rate implying the more stable catalyst. More specifically, in a dehydrogenationprocess, activity commonly refers to the amount of conversion that takes place for a given dehydrogenatable hydrocarbon at a specified severity level and is typically measured on the basis of disappearance of the dehydrogenatable hydrocarbon; selectivity is typically measured by the amount, calculated on a mole percent of converted dehydrogenatable hydrocarbon basis,

of the desired dehydrogenated hydrocarbon obtained at a particular activity level; and stability is typically equated to the rate of change with time of activity as measured by disappearance of the dehydrogenatable hydrocarbon and of desired hydrocarbon produced. Accordingly, the major problem facing workers in the hydrocarbon dehydrogenation art is the development of a more active and selective catalytic composite that has good stability characteristics.

I have now found a catalytic composite which possesses improved activity, selectivity, and stability when it is employed in a process for the dehydrogenation of dehydrogenatable hydrocarbons. In particular, I have determined that a superior dehydrogenation catalyst comprises a combination of catalytically effective amounts of a platinum group component, a nickel component, a Group IVA metallic component, and an alkali or alkaline earth component with a porous carrier material. This catalyst can, in turn, enable the performance of a dehydrogenation process to be substantially improved. Moreover, particularly good results are obtained when this catalyst is utilized in the dehydrogenation of long chain normal paraffins to produce the corresponding normal mono-olefins with minimization of side reactions such as skeletal isomerization, aromatization and cracking. In sum, the current invention involves the significant finding that a combination of a nickel component and a Group IVA metallic component can be utilized to bene ficially interact with a platinum-containing dehydrogenation catalyst.

It is, accordingly, one object of the present invention to provide a novel method for dehydrogenation of dehydrogenatable hydrocarbons utilizing a catalytic composite containing a platinum group component, a nickel component, a Group IVA metallic component, and an alkali or alkaline earth component combined with a porous carrier material. A second object is to provide a novel catalytic composite having superior performance characteristics when utilized in a dehydrogenation process. Another object is to provide an improved method for the dehydrogenation of normal parafiin hydrocarbons to produce normal mono-olefins. Yet another object is to improve the performance of a platinum-containing dehydrogenation catalyst by using a combination of relatively inexpensive components, nickel and a Group IVA metal, to beneficially interact and promote the platinum metal.

In brief summary, one embodiment of the present invention involves a novel catalytic composite involving a combination of catalytically efiective amounts of a platinum group, a Group IVA metallic component, a nickel component, and an alkali or alkaline earth component with a porous carrier material.

A second more specific embodiment relates to a catalytic composite comprising a combination of catalytically effective amounts of a platinum component, a nickel component, a germanium component and an alkali or alkaline earth component with an alumina carrier material.

A third embodiment comprehends a method for dehydrogenating a dehydrogenatable hydrocarbon which essentially invovles contacting the dehydrogenatable hydrocarbon at dehydrogenation conditions with the catalytic composite defined in the first embodiment,

Another embodiment involves a method for the selective dehydrogenation of a normal paraflin hydrocarbon containing about 4 to 30 carbon atoms per molecule to the corresponding normal mono-olefins. The method essentially involving contacting the normal paraflin hydrocarbons and hydrogen at dehydrogenation conditions with a catalytic composite of the type defined in the first embodiment.

Other objects and embodiments of the present invention include specific details regarding essential and preferred ingredients of the disclosed catalytic composite, preferred amounts of ingredients for this composite, suitable methods of composite preparation, dehydrogenatable hydrocarbons that are preferably used with this catalyst in a dehydrogenation process, operating conditions that can be utilized with this catalyst in a dehydrogenation process and the like particulars. These objects and embodimentsare disclosed in the following detailed explanation of the various technical aspects of the present invention. It is to be noted that the terms catalyst and catalytic composite are used herein in an equivalent, andinterchangeable manner.

Regarding the dehydrogenatable hydrocarbon that is subjected to the instant method, it can, in general, be an organic compound having 2 to 30 carbon atoms per molecule and containing at least 1 pair of adjacent carbon atoms having hydrogen attached thereto. That is, it is intended to include within the scope of the present invention the dehydrogenation of any organic compound capable of being dehydrogenated to produce products containing the same number of carbon atoms but fewer hydrogen atoms, and capable of being vaporized at the dehydrogenation conditions used herein. More particularly, suitable dehydrogenatable hydrocarbons are:,

aliphatic compounds containing 2 to 30 carbon atoms per molecule, alkylaromatic hydrocarbons where the alkyl group contains 2 to 6 carbon atoms, and naphthenes or alkyl-substituted naphthenes. Specific examples of suitable dehydrogenatable hydrocarbons are: ,(l) alkanes such as ethane, propane, n-butane, isobutanes, n-pentane,

isopentane, n-hexane, 2-methy1pentane, 2,2-dirnethylbutane, n-heptane, n-octane, Z-methylhexane, 2,2,3-tri-- mono-olefin which can, in turn, be alkylated with benzene and sulfonated to make alkylbenzene sulfonate detergents having superior biodegradability. Likewise, n-alkanes having 10 to 18 carbon atoms per molecule can be de.-.. hydrogenated to the corresponding normal mono-olefin. which, in turn, can be sulfated or sulfonated to makeexcellent detergents. Similarly, n-alkanes having 6 to 10.

carbon atoms per molecule can be dehydrogenated. to

form the corresponding mono-olefins which can, in .turn,.

be hydrated to produce valuable alcohols. Preferred feed streams for the manufacture of detergent intermediates contain a mixture of 4 or 5 adjacent normal parafiin Cu to 'C15.

homologues such as C to C C to C and the like mixtures.

An essential feature of the present invention involves the use of a catalytic composite comprising acombination of catalytically effective amounts of a platinum group component, a nickel component, a Group IVA metallic component, and an alkali or alkaline earth component with a porous carrier material.

Considering first the porous carrier material, it-is preferred that the material be a porous, adsorptive, highsurface area support having a surface area of about 25 to about 500 m. /g. The porous carrier materialshouldjbe relatively refractory to the conditions utilized in thedehydrogenation process and it. is intended to include within the scope of the present invention carrier materials which have traditionally been utilized in hydrocarbon conversion catalysts such as: .(l) activated carbon, coke, or charcoal; (2 silica or silica gel, silicon carbide, clays, and silicates including those synthetically prepared and naturally occurring, which may or may not be acid treated for example, attapulgus clay, china clay, diatomaceous earth, fullersearth, kaolin, kieselguhr etc.; (3) ceramics porcelain, crushedfirebrick, bauxite, (4) refractory inorganic oxides. such. as alumina, titanium dioxide, zirconium dioxide, chromiurnoxide, zinc oxide, magnesia, thoria, boria, silica-alumina, silica magnesia, chromiaalumina, aluminaboria, silica-zirconia, etc.; (5 crystal line aluminosilicates such as naturally occurring or synthetica'lly prepared mordenite and/or faujasite, either in the hydrogenform orin a form which has been treated with multivalent cations; and, (6) combination of elements from one or more of these groups. The preferred porous carrier materialsforuse inv the present invention are refractory inorganic I oxides, with best results obtainedwith an alumina carrier material. Suitable alumina materials .are the crystlline aluminas known as the gamma-, eta-,wand theta-aluminas, with gama-alumina giving best results. In addition, in some embodiments, the alumina carrier material may contain minor proportions of other well known refractory inorganic oxides such as silica, zirconia, magnesia, etc.; however, the preferred support is substantially pure. gamma-alumina. Preferred carrier materials have an apparent bulk density of about 0.3 to about 0.7 g./cc. and surface area characteristics such that the average pore diameter is about 20 to 300 Angstroms, the pore volume is about 0.1 to about 1 ml./g. and the surface area is about 100 to about 500 m. /g. In general, excellent results are typically obtained with gamma-alumina carrier material which is used in theformof spherical particles having: a relatively small diameter (i.e., typically about A inch), an apparent bulk density of about 0.5 g./cc., a pore volume of about 0.4 ml./g..and a surface area of about 175 m. /g.

The preferred alumina carrier material may be prepared in any suitable manner and may be synthetically prepared or natural occurring. Whatever type of alumina is employed it may be activated prior to use by one or more treatments including drying, calcination, steaming, etc., and it may be in a form known as activated alumina, activated alumina of commerce, porous alumina, alumina gel, etc. For example, the alumina carrier may be prepared by adding a suitable alkaline reagent, such as ammonium hydroxide to a salt of aluminum such as aluminum chloride, aluminum nitrate, etc., in an amount to form an aluminum hydroxide gel which upon drying and calcining is converted. to alumina. The alumina carrier may be formed in any desired shape such as spheres, pills, cakes, extrudates, powders, granules, etc., and utilized in any desired size; For the purpose of the present invention a particularly preferred form of alumina is the sphere; and alumina spheres may be continuously manufactured by the well known oil drop method which comprises: forming an alumina-hydrosol'by any of the techniques taught in the art and-preferably by reacting aluminum metal with hydrochloric acid; combining the resulting hydrosol with a suitable gelling agent; and dropping'the resultant mixture into an oil bath maintained at elevated temperatures. The droplets of the mixture remain in the oil bath until they set-and"-form hydrogel spheres. The spheres are then' continuously withdrawn from the oil bath and typically subjected to'specific aging treatments inoil'and an-ammoniacal'solution to further improve their physical characteristicslThe resulting aged and gelled particles are then washed and dried at a relatively low temperature of about 300 F. to about 400 F. and subjected to'a' calcination procedure'at a temperature of about 850 F. to about 1300" F. for a period of about 1 to-20h0'ur 's.'It-is a good practice to subject the calcined particles to a high temperaturetreatment with steam in order-'to remove undesired acidic components. This method efiects conversion of the alumina hydrogel to the corresponding crystalline gamma-alumina. See the teachings of U.S. Pat. No. 2,620,314 for additional details.

One essential constituent of the instant catalytic composite is the Group IVA metallic component. By the use of the generic term Group IVA metallic component it is intended to cover the metals and compounds of the metals of Group IVA of the Periodic Table. More specifically, it is intended to cover: germanium and the compounds of germanium; tin and the compounds of tin; lead and the compounds of lead; and mixtures of these metals and/or compounds of metals. This Group IVA metallic component may be present in the catalytic composite as an elemental metal, or in chemical combination with one or more of the other ingredients of the composite, .or as a.

chemical compound of the Group IVA metal such as the oxide, sulfide, halide, oxyhalide, oxychloride, aluminate, and the like compounds. Based on the evidence currently available, it is believed that best results are obtained when the Group IVA metallic component exists in the final composite in an oxidation state above that of the elemental metal, and the subsequently described oxidation and reduction steps, that are preferably used in the preparation of the instant composite, are believed to result in a catalytic composite which contains an oxide of the Group IVA metallic component such as germanium oxide, tin oxide, and lead oxide. Regardless of the state in which this component exists in the composite, it can be utilized therein in any amount which is catalytically elfective with the preferred amount being about 0.01 to about 5 wt. percent thereof, calculated on an elemental basis. The exact amount selected within this broad range is preferably determinedas a function of the particular Group IVA metal that is utilized. For instance, in the case where this component is lead, it is preferred to select the amount of this component from the low end of this rangenamely, about 0.01 to about 1 wt. percent. Additionally, it is preferred to select the amount of lead as a function of the amount of the platinum group component as explained hereinafter. In the case where this component is tin, it is preferred to select from a relatively broader range of about- 0.05 to about 2 wt. percent thereof. And, in the preferred case, where this component is germanium, the selection can be made from the full breadth of the stated range-- specifically, about 0.01 to about 5 wt. percent, with best results at about 0.05 to about 2 wt. percent.

This Group IVA component may be incorporated in the composite in any suitable manner known to the art such as by physical admixture, coprecipitation or cogellation with the porous carrier material, ion exchange with the carrier material, or impregnation of the carrier material at any stage in its preparation. It is to be noted that it is intended to include within the scope of the present invention all conventional procedures for incorporating a metallic component in a catalytic composite, and the particular method of incorporation used is not deemed to be an essential feature of the present invention. However, best results are believed to be obtained when the Group IVA component is uniformly distributed throughout the porous carrier material. One acceptable method of incorporating the Group IVA component into the catalytic composite involves cogelling the Group IVA component during the preparation of the preferred carrier material, alumina. This method typically involves the addition of a suitable soluble compound of the Group IVA metal of in terest to the alumina hydrosol. The resulting mixture is then comingled with a suitable gelling agent, such as a relatively weak alkaline reagent, and the resulting mixture is thereafter preferably gelled by dropping into a hot oil bath as explained hereinbefore. After aging, drying and calcining the resulting particles there is obtained an intimate combination of the oxide of the Group IVA metal and alumina. One preferred method of incorporating this component into the composite involves utilization of a soluble decomposable compound of the particular Group IVA metal of interest to impregnate the porous carrier material either before, during or after the carrier material is calcined. In general, the solvent used during this impregnation step is selected on the basis of its capability to dissolve the desired Group IVA compound without affecting the porous carrier material which is to be impregnated; ordinarily, good results are obtained when water is the solvent; thus the preferred Group IVA compounds for use in this impregnation step are typically watersoluble and decomposable. Examples of suitable Group IVA compounds are: germanium difluoride, germanium dioxide, germanium tetrafluoride, germanium monosulfide, tin dibromide, tin dibromide di-iodide, tin dichloride di-iodide, tin chromate, tin difluoride, tin tetrafluoride, tin" tetraiodide, tin sulfate, tin tartrate, lead acetate, lead bromate, lead bromide, lead chlorate, lead chloride, lead citrate, lead formate, lead lactate, lead malate, lead nitrate, lead nitrite, lead dithionate, and the like compounds. In the case where the Group IVA component is germanium, a preferred impregnation solution is germanium tetrachloride dissolved in anhydrous alcohol. In the case of tin, tin chloride dissolved in water is preferred. Regardless of which impregnation solution is utilized, the Group IVA component can be impregnated either prior to, simultaneously with, or after the other metallic components are added to the carrier material. Ordinarily, best results are obtained when this component is impregnated simultaneously with the other metallic components of the composite. Likewise, best results are ordinarily obtained when the Group IVA component is germanium or a compound of germanium.

Regardless of which Group IVA compound is used in the preferred impregnation step, it is important that the Group IVA metallic component be uniformly distributed throughout the carrier material. In order to achieve this objective it is necessary to maintain the pH of the impregnation solution in a range of about 1 to about 7 and to dilute the impregnation solution to a volume which is substantially in excess of the volume of the carrier material which is impregnated. It is preferred to use a volume ratio of impregnation solution to carrier material of at least 1:1 and preferably about 2:1 to about 10:1 or more. Similiarly, it is preferred to use a relatively long contact time during the impregnation step ranging from about A hour up to about /2 hour or more before drying to remove excess solvent in order to insure a high dispersion of the Group IVA metallic component on the carrier material. The carrier material is, likewise preferably constantly agitated during this preferred impregnation step.

A second essential ingredient of the subject catalyst is the platinum group component. Although the process of the present invention is specifically directed to the use of a catalytic composite containing platinum, it is intended to include other platinum group metals such as palladium, rhodium, ruthenium, osmium, and iridium. The platinum group component such as platinum, may exist within the final catalytic composite as a compound such as an oxide, sulfide, halide, etc., or as an elemental metal or in chemical combination with the other ingredients of the catalyst. The preferred state for this component is the elemental metal. Generally, the amount of the platinum group component present in the final catalyst is small compared to the quantities of the other components combined therewith, although it can be utilized in any amount which is catalytically effective. In fact, the platinum group component generally comprises about 0.01 to about 2 wt. percent of the final catalytic composite, calculated on an elemental basis. Excellent results are obtained when the catalyst contains about 0.05 to about 1 wt. percent of the platinum group metal. The preferred platinum group component is platinum or a compound of platinum, although good results are obtained when it is palladium or a compound of palladium.

The platinum group component may be incorporated in the catalytic composite in any suitable manner such as physical admixture, coprecipitation or 'cogellation, ion-exchange, or impregnation. The preferred method of preparing the catalyst involves the utilization of a soluble, decomposable compound of a platinum group metal to impregnate the carrier material. Thus, the platinum group component may be added to the support by commingling the latter with an aqueous solution of chloroplatinic acid. Other water-soluble compounds of platinum group metals may be employed in impregnation solutions and include ammonium chloroplatinate, bromoplatinic acid, platinum dichloride, platinum tetrachloridehydrate, platinum dichlorocarbonyl dichloride, dinitrodiaminoplatinum, palladium chloride, palladium nitrate, palladium sulfate and chloropalladic acid etc. The utilization of a platinum chloride compound, such as chloroplatinic acid is ordinarily preferred. Hydrogen chloride, nitric acid, or the like acid is also generally added to the impregnation solution in order to further facilitate the distribution of the metallic component. In addition, it is generally preferred to impregnate the carrier material after it has been calcined in order to minimize the risk of washing away the valuable platinum metal compounds; however, in some cases it may be advantageous to impregnate the carrier material when it is in a gelled state.

Yet another essential ingredient of the present catalytic composite is a nickel component. This component may be present in the composite as an elemental metal, or in chemical combinations with one or more of the other ingredients of the composite, or as a chemical compound of nickel such as nickel oxide, sulfide, halide, oxychloride, aluminate and the like. Best results are believed to be obtained when the composite contains this component in the elemental state, and the preferred preparation procedure which is given in Example I is believed to result in this condition. The nickel component may be utilized in the composite in any amount which is catalytically effective, with the preferred amount being about 0.01 to about 5 wt. percent thereof, calculated on an elemental nickel basis. Typically, best results are obtained with about 0.05 to about 2 wt. percent nickel. It is, additionally, preferred to select the specific amount of nickel from within this broad weight range as a function of the amount of the platinum group component, on an atomic basis, as is explained hereinafter.

The nickel component may be incorporated into the catalytic composite in any suitable manner known to those skilled in the catalyst formulation art.

In addition, it may be added at any stage of the preparation of the composite-either during preparation of the carrier material or thereafter'-since the precise method of incorporation used is not deemed to be critical. However,=

volves cogelling the nickel component during the prepara-.

tion of the preferred carrier material, alumina. This procedure usually comprehends the addition of a soluble, de-' composable compound of nickel such as nickel chloride to the alumina hydrosol before it is gelled. The resulting mixture is then finished by conventional gelling, aging, drying and calcination steps as explained hereinbefore. One pre-, ferred way of incorporating this component is an impregnation step wherein the porous carrier material is impregnated with a suitable nickel-containing solution either be-v fore, during or after the carrier material is calcined. Preferred impregnation solutions are aqueous solutions of water-soluble, decomposable nickel compounds such as nickel bromate, nickel bromide, nickel perchlorate, nickel chloride, nickel fluoride, nickel iodide, nickel nitrate, nickel. sulfate, and the like compounds, Best results are ordinarily, obtained when the impregnation solution is an aqueous so-.

lution of nickel chloride or nickel nitrate. This nickel component can be added to the carrier material, either prior to, simultaneously with, or after the other metallic components are combined therewith.

- Yet another essential ingredient of the catalyst used in the present invention is the alkali or alkaline earth component. More specifically, this component is selected from the group consisting of the compounds of the alkali metals,cesium, rubidium, potassium, sodium, and lithium and of the alkaline earth metals-calcium, strontium, barium, and magnesium. This component may exist within the catalytic composite as a relatively stable compound such as the oxide or sulfide, or in combination with one or more of the other components of the composite, or in combination with the carrier material such as, for example, in the form of a metal aluminate. Since, as is explained hereinafter, the composite containing the alkali or alkaline earth is always calcined in an air atmosphere before use in the conversion of hydrocarbons, the most likely state this component exists in during use in dehydrogenation is the metallic oxide. Regardless of what precise form in which it exists in the composite, the amount of this component utilized is preferably selected to provide a composite containing about 0.1 to about wt. percent of the alkali or alkaline earth metal, and, more preferably, about 0.25 to about 3.5 wt. percent. Best results are obtained when this component is a compound of lithium or potassium.

This alkali or alkaline earth component may be combined with the porous carrier material in any manner known to those skilled in the art such as by impregnation, coprecipitation, physical mixture, ion-exchange and the like procedures. The preferred procedure, however, involves impregnation of the carrier material either before, during or after it is calcined, or before, during or after the other materials are added to the carrier material. Best results are ordinarily obtained when this component is added to the carrier material after the other metallic components because the alkali metal or alkaline earth metal acts to neutralize some of. the acid used in the preferred impregnation procedure for these metallic components. In fact, it is preferred to add the platinum group, nickel and Group IVA metallic components to the carrier material, oxidize the resulting composite in an air stream at a high temperature (i.e., typically about 600 to 1000 F.), then treat the resulting oxidized composite with a mixture of air and steam in order to remove residual acidity and thereafter add the alkali metal or alkaline earth component. Typically, the impregnation of the carrier material with this component is performed by contacting the carrier material with a solution of a suitable decomposable compound or salt of the desired alkali or alkaline earth metal. Hence, suitable compounds include the alkali metal or alkaline earth metal halides, sulfates, nitrates, acetates, carbonates, phosphates and the like compounds. For example, excellent results are obtained by impregnating the carrier material after .the platinum group, nickel and Group IVA metallic components have been combined therewith, with an aqueous solution of lithium nitrate or potassium nitrate. I p

7 Regarding the preferred amounts of the various metallic components of the subject catalyst, I have found it to be a good practice tospecify the amounts of the nickel component, the Group IVA metallic component and the alkali oralkaline earth component, as a function of the amount of the platinum group component. On this basis, the amount ofthe. nickel component is ordinarily selected so that theatomic ratio of nickel to the platinum group metal is about 0.2:1 to about 20:1,. with the preferred rangebeingabout 1:} to 10:1. Similarly, the amount of the Group IVA metallic component is ordinarily selected to produce, a composite having an atomic ratio of Group IVA metal toplatinum group metal Within the broad range of'about 0.05:1 to about 10:1. However, for the Group IVA metal to platinum group metal ratio, the best practice isto select this ratio on the basis of the following preferred range for the individual species: (1), for germanium it is about 0.3:1 to 10:1, with the most preferred range being about 0.6:1 to about 6:1; (2) for tin, it is about 0.1:1 to 3:1, with the most preferred range being about 0.5:1 to 1.5:1; and (3) for lead, it is about 0.05:1 to 09:1, with the most preferred range being about 0.1:1 to 0.75:1. Similarly, the amount of the alkali or alkaline earth component is ordinarily selected to produce a composite having an atomic ratio of alkali or alkaline earth metal to platinum group metal of about 5 :1 to about 50:1 or more, with the preferred range being about 10:1 to about 25:1.

Another significant parameter for the instant catalyst is the total metals content which is defined to be the sum of the platinum group component, the nickel component, the Group IVA metallic component, and the alkali or alkaline earth component, calculated on an elemental metal basis. Good results are ordinarily obtained with the subject catalyst when this parameter is fixed at a value of about 0.2 to about 5 wt. percent, with best results ordinarily achieved at a metals loading of about 0.4 to about 4 wt. percent.

Integrating the above discussion of each of the essential components of the catalytic composite used in the present invention, it is evident that a particularly preferred catalytic composite comprises a combination of a platinum component, a nickel component, a germanium component and an alkali or alkaline earth component with an alumina carrier material in amounts suflicient to result in the composite containing from about 0.05 to about 1 Wt. percent platinum, about 0.05 to about 2 wt. percent nickel, about 0.05 to about 2 wt. percent germanium, and about 0.25 to about 3.5 wt. percent of the alkali or alkaline earth metal.

Regardless of the details of how the components of the catalyst are combined with the porous carrier material, the resulting composite generally will be dried at a tem perature of about 200 F. to about 600 F. for a period of from about 2 to 24 hours or more, and finally calcined at a temperature of about 600 F. to about 1100 F. in an air atmosphere for a period of about 0.5 to 10 hours, preferably about 1 to about 5 hours, in order to substantially convert the metallic components to the oxide form. When acidic components are present in any of the reagents used to effect incorporation of one of the components of the subject composite, it is a good practice to subject the resulting composite to a high temperature treatment with steam or with a mixture of steam and air, either after or before the calcination step described above, in order to remove as much as possible of the undesired acidic component. For example, when the platinum group component is incorporated by impregnating the carrier material with chloroplatinic acid, it is preferred to subject the resulting composite to a high temperature treatment with steam in order to remove as much as possible of the undesired chloride.

It is preferred that the resultant calcined catalytic composite be subjected to a substantially water-free reduction prior to its use in the conversion of hydrocarbons. This step is designed to insure a uniform and finely divided dispersion of the metallic components throughout the carrier material. Preferably, substantially pure and dry hydrogen (i.e., less than 20 vol. p.p.m. H O) is used as the reducing agent in this step. The reducing agent is contacted with the calcined composite at a temperature of about 800 F. to about 1200 F., a gas hourly space velocity of about to about 5,000 hrr and for a period of time of about 0.5 to 10 hours or more, effective to substantially reduce atleast the platinum group component. This reduction treatment may be performed in situ as part of a start-up sequence if precautions are taken to predry the plant to a substantially water-free state and if substantially waterfree hydrogen is used.

Theresulting reduced catalytic composite may, in some cases, be beneficially subjected to a presulfiding operation designed to .incorporate in the catalytic composite from about 0.05 to about 0.5 wt. percent sulfur calculated on an elemental basis. Preferably, this presulfiding treatment :1 1 takes place in the presence of hydrogen and a suitable sulfur-containing compound such as hydrogen sulfide, lower molecular weight mercaptans, organic sulfides, etc. Typically, this procedure comprises treating the reduced catalyst with a sulfiding gas such as a mixture containing a mole ratio of H to H 5 of about :1 at conditions sufficient to effect the desired incorporation of sulfur, generally including a temperature ranging from about 50 F. up to about 1100 F. or more. This presulfiding step can be performed in situ or ex situ.

According to the method of the present invention, the dehydrogenatable hydrocarbon is contacted with a catalytic composite of the type described above in a dehydrogenation zone at dehydrogenation conditions. This contacting may be accomplished by using the catalyst in a fixed bed system, a moving bed system, a fluidized bed system, or in a batch type operation; however, in view of the danger of attrition losses of the valuable catalyst and of well known operation advantages, it is preferred to use a fixed bed system. In this system, the hydrocarbon feed stream is preheated by any suitable heating means to the desired reaction temperature and then passed into a dehydrogenation zone containing a fixed bed of the catalyst type previously characterized. It is, of course, understood that the dehydrogenation zone may be one or more separate reactors with suitable heating means therebetween to insure that the desired conversion temperature is maintained at the entrance to each reactor. It is also to be noted that the reactants may be contacted with the catalyst bed in either upward, downward, or radial flow fashion, with the latter being preferred. In addition, it is to be noted that the reactants may be in the liquid phase, a mixed liquid-vapor phase, or a vapor phase when they contact the catalyst, with best results obtained in the vapor phase.

Although hydrogen is the preferred diluent for use in the subject dehydrogenation method, in some cases other art-recognized diluents may be advantageously utilized such as steam, methane, carbon dioxide, and the like diluents. Hydrogen is preferred because it serves the dualfunction of not only lowering the partial pressure of the dehydrogenatable hydrocarbon, but also of suppressing the formation of hydrogen-deficient, carbonaceous deposites on the catalytic composite. Ordinarily, hydrogen is utilized in amounts sufficient to insure a hydrogen to hydrocarbon mole ratio of about 1:1 to about :1, with best results obtained in the range of about 1.5:1 to about 10:1. The hydrogen stream charged to the dehydrogenation zone will typically be recycle hydrogen obtained from the eflluent stream from this zone after a suitable separation step.

When hydrogen is used as the diluent, a preferred practice is to add water or'a water-producing compound to the dehydrogenation zone. This water additive may be included in the charge stock, or in the hydrogen stream, or in both of these, or added independently of these. Ordinarily, it is preferred to inject the necessary water by saturating at least a portion of the input hydrogen stream with water. Good results are also obtained when a waterproducing compound such as a C to C alcohol is added to the charge stock. Regardless of the source of the water, the amount of equivalent water added should be sufficient to maintain the total amount of water continuously entering the hydrogenation zone in the range of about 50 to about 10,000 wt. p.p.m. of the charge stock, with best results obtained at a level corresponding to about 1500 to 5000 wt. ppm. of the charge stock.

Concerning the conditions utilized in the process of the present invention, these are generally selected from the conditions well known to those skilled in the art for the particular dehydrogenatable hydrocarbon which is charged to the process. More specifically, suitable conversion temperatures are selected from the range of about 700 to about 1200 F., with a value being selected from the lower portion of this range for the more easily dehydrogenated hydrocarbons such as the long chain normal paraffins and from the higher portion of this range for the more difficultly dehydrogenated hydrocarbons such as propane, butane, and the like hydrocarbons. For example, for the dehydrogenation of C to C normal paraffins, best results are ordinarily obtained at a temperature of about 800 to about 950 F. The pressure utilized is ordinarily selected at a value which is as low as possible consistent with the maintenance of catalyst stability, and is usually about 0.1 to about 10 atmospheres, with best results ordinarily obtained in the range of about .5 to about 3 atmospheres. In addition, a liquid hourly space velocity (calculated on the basis of the volume amount, as a liquid, of hydrocarbon charged to the dehydrogenation zone per hour divided by the volume of the catalyst bed utilized) is selected from the range of about 1 to about 40 hrr with best results for the dehydrogenation of long chain normal paraffins typically obtained at a relatively high space velocity of about 25 to 35 hf.'

Regardless of the details concerning the operation of the dehydrogenation step, an efiiuent stream will be withdrawn therefrom. This effiuent will contain unconverted dehydrogenatable hydrocarbons, hydrogen, and products of the dehydrogenation reaction. This stream is typically cooled and passed to a separating zone wherein a hydrogen-rich vapor phase is allowed to separate from a hydrocarbon-rich liquid phase. In general, it is usually desired to recover the unreacted dehydrogenatable hydrocarbon from this hydrocarbon-rich liquid phase in order to make the dehydrogenation process economically attractive. This recovery step can be accomplished in any suitable manner known to the art such as by passing the hydrocarbon-rich liquid phase through a bed of suitable adsorbent material which has the capability to selectively retain the dehydrogenated hydrocarbons contained therein or by contacting same with a solvent having a high selectivity for the dehydrogenated hydrocarbon or by a suitable fractionation scheme where feasible. In the case Where the dehydrogenated hydrocarbon is a mono-olefin, suitable adsorbents having this capability are activated silica gel, activated carbon, activated alumina, various types of specially prepared molecular sieves, and the like adsorbents. In another typical case, the dehydrogenated hydrocarbons can be separated from the unconverted dehydrogenatable hydrocarbons by utilizing the inherent capability of the dehydrogenated hydrocarbons to enter into several well known chemical reactions such as alkylation, oligomerization, halogenation, sulfonation, hydration, oxidation, and the like reactions. Irrespective of how the dehydrogenated hydrocarbons are separated from the unreacted hydrocarbons, a stream containing the unreacted dehydrogenatable hydrocarbons will typically be recovered from this hydrocarbon separation step and recycled to the dehydrogenation step. Likewise, the hydrogen phase present in the hydrogen separating zone will be withdrawn therefrom, a portion of it vented from the system in order to remove the net hydrogen make, and the remaining portion is typically recycled, through suitable compressing means, to the dehydrogenation step in order to provide diluent hydrogen therefor.

In a preferred embodiment of the present invention wherein long chain normal paraffin hydrocarbons are dehydrogenated to the corresponding normal mono-olefins, a preferred mode of operation of this hydrocarbon separation step involves an alkylation reaction. In this mode, the hydrocarbon rich liquid phase withdrawn from the separat ing zone is combined with a stream containing an alkylatable aromatic and the resulting mixture passed to an alkylaaromatic while the unconverted normal parafiins remain substantially unchanged. The eflluent stream from the alkylation zone can then be easily separated, typically by means of a suitable fractionation system, to allow recovery of the unreacted normal paraflins. The resulting stream ofj-unconverted normal paraffins is then usually recycled to the dehydrogenation-step of the present invention.

i-Thetollowing working examples are introduced to illustrate further the novelty, mode of operation, utility and benefits associated with the dehydrogenation method and catalytic composite of the present invention. These examples are, intended to be illustrative rather than restric- ..'.1?hes e.exarnples are all performed in a laboratory scale dehydrogenation plant comprising a reactor, a hydrogen sepagating -zone,... a heating means, cooling means, pump g means, compressing means, and the like equipment.

plant, the feedstream containing the dehydrogenat- I rocarb on is combined with a hydrogen stream and theires ultantimixture heated to the desired conversion temperature, which refers herein to the temperature mainta fid .at. the inlet ,to the reactor. The heated mixture is the ,pa's sed into contact. with the catalyst which is mainfined as a.fixd ,,bed of catalyst particles in the reactor. Thepressu'res" reported herein are recorded at the outlet frommth'e reactor. An efiluent stream is withdrawn from reactor, cooled, and. passed into the separating zone Wher In va hydroge nvgas'phase separates from a hydroca ori'rich liquid phase containing dehydrogenated hydrocarbons, unconverted dehydrogenatable hydrocarbons and a minor amount of side products of the dehydrogenation reaction. A portiQn of ,the hydrogen-rich gas phase is recoyered as excessrecycle gas with the remaining portion being continuously recycled through suitable compressiye means to the heating zone as described above. The p arbon rich liquid phase from the separating zone is wi drawn therefrom as subjected to analysis to determine co nversionfandselectivity for the desired dehydrogenated h' y 'arjbon as will be indicatedin the examples. Connumbers' of the dehydrogenatable hydrocarbon repo' r ed herein are all calculated on the basis of disapp earance of the dehydrogenatable hydrocarbon and are expressed. in mole percent. Similarly, selectivity numbers arefr'eported on the basis of mole ofdesired hydrocarbon produced'per 100 moles of dehydrogenatable hydrocarbon 9nY u q of the'catalysts 'utilized in these examples are prepared "according to the following general method with suitable modifications in stoichiornetry to achieve the compositi'onsreported in each example. First, an alumina carrier material comprising inch spheres is prepared by for inga'njalur'ninum hydroxyl chloride sol by dissolving s stjantially pure aluminum pellets in a hydrochloric a d'i solutionadding hexam'ethylenetetramine to the sol, g ng'f'tliejresulting 'solution by dropping it into an oil bath to form spherical particles of an alumina hydrogel, aging, and washing the resulting particles with an ammoniacal solution and finally dry in g, calcining, and steaming the aged and washed particles to form spherical particles of gamma-alumina containing substantially less than Ogl-fwtpercentcombined chloride. Additional details as t thismethodof preparingthisalumina carrier material a'rclgivengin' the .teachings, of .U.S."Pat. No. 2,620,314.

Second, a measured amount of germanium tetrachloride is dissolved in anhydrous'ethanol. The resulting solution is aged atroom temperature until an equilibrium condition is established'therein. A n aqueous solution containing chloroplatinic acid, nickel chloride, and hydrochloric acid is also prepared. The two solutions are then intimately admixed and used to impregnate the gammaalumina particles. The amounts of the various reagents are carefully selected to yield final catalytic composites containing the required amounts of platinum, nickel and germanium. In order to insure uniform distribution of metallic components throughout the carrier material, this impregnation step is performed by adding the alumina particles to the impregnation mixture with constant agitation. The impregnation mixture is maintained in contact with the alumina particles for a period of about /2 hour at a temperature of 70 F. thereafter, the temperature of the impregnation mixture is raised to about 225 F. and the excess solution is evaporated in a period of about one hour. The resulting dried particles are then subjected to a calcination treatment in an air atmosphere at a temperature of about 500 to about 1000 F. for about 2 to 10 hours. Thereafter, the resulting calcined particles are treated with an air stream containing from about 10 to about 30% steam at a temperature of about 800 to about 1000 F. for an additional period from about 1 to about 5 hours in order to further reduce the residual combined chloride in the composite.

Finally, the alkali or alkaline earth metal component is added to the resulting calcined particles in a second impregnating step. This second impregnation step involves contacting the calcined particles with an aqueous solution of a suitable decomposable salt of the desired alkali or alkaline earth component. For the composites utilized in the present examples, the salt is either lithium nitrate or potassium nitrate. The amount of this salt is carefully chosen to result in a final composite having the desired composition. The resulting alkali impregnated particles are then dried, calcined and steamed in exactly the same manner as described above following the first impregnation step.

In all the examples the catalyst is reduced during startup by contacting with hydrogen at an elevated temperature and thereafter sulfided with a mixture of H and H S.

EXAMPLE I The reactor is loaded with 100 cc.s of a catalyst containing, on an elemental basis, 0.375 wt. percent platinum, 0.5 wt. percent nickel, 0.25 wt. percent germanium, 0.5 wt. percent lithium and less than 0.15 wt. percent chloride. The feed stream utilized is commercial grade isobutane containing 99.7 wt. percent isobutane, 0.3 wt. percent normal butane. The feed stream is contacted with the catalyst at a temperature of 1065 F., a pressure of 10 p.s.i.g., a liquid hourly space velocity of 4.0 hr.- and a hydrogen to hydrocarbon mole ratio of 2:1. The dehydrogenation plant is lined-out at these conditions and a 20 hour test period commenced. The hydrocarbon product stream from the plant is continuously analyzed by GLC (gas-hquid chromatography) and a high conversion of isobutane is observed with good selectivity for isobutylene.

EXAMPLE II The catalyst contains, on an elemental basis, 0.375 wt. percent platinum, 0.5 wt. percent germanium, 0.25 Wt. percent nickel, 0.5 wt. percent lithium, and less than 0.15 wt. percent combined chloride. The feed stream is commercial grade normal dodecane. The dehydrogenation reactor is operated at a temperature of 870 F., a pressure of 10 p.s.i.g., a liquid hourly space velocity of 32 hr.- and a hydrogen to hydrocarbon mole ratio of 8:1. After a line-out period, a 20 hour test period is performed during which the average conversion of the normal dodecane is maintained at a high level with a selectivity for dodecene of about EXAMPLE HI The catalyst is the same as utilized in Example II. The feed stream is normal tetradecane. The conditions utilized are a temperature of 840 F., a pressure of 20 p.s.i.g., a liquid hourly space velocity of 32 hr.- and a hydrogen to hydrocarbon mole ratio of 8:1. After a line-out period,- a 20 hour test shows an average conversion of approximately 12% and a selectivity for tetradecene of above about 90%.

EXAMPLE IV The catalyst contains, on an elemental basis, 0.6 wt. percent platinum, 0.2 wt. percent nickel, 0.5 wt. percent germanium and 0.6 wt. percent lithium, with combined chloride being less than 0.2 wt. percent. The feed stream is substantially pure normal butane. The conditions utilized are a temperature of 950 F., a pressure of 15 p.s.i.g., a

a 20 hour test is performed and excellent conversion of the normal butane to butene is observed.

EXAMPLE V The catalyst contains, on an elemental basis, 0.375 wt. percent platinum, 0.375- wt. percent nickel, 0.5 wt. percent germanium, 2.8 wt. percent potassium, and less than 0.2 wt. percent combined chloride. The feed stream is commercial grade ethylbenzene. The conditions utilized are a pressure of 15 p.s.i.g., a liquid hourly space velocity of 32 hrr a temperature of 950 F. and a hydrogen to hydrocarbon mole ratio of 8:1. During a 20 hour test period, at least 85% of equilibrium conversion of ethylbenzene is observed with high selectivity for styrene.

It is intended to cover by the following claims all changes and modifications of the above disclosure of the present invention that would be self-evident to a man of ordinary skill in the catalyst formulation art or the hydrocarbon dehydrogenation art.

I claim as my invention:

1. A method for dehydrogenating a dehydrogenatable hydrocarbon comprising contacting the hydrocarbon at dehydrogenation conditions with a catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a nickel component, a Group IVA metallic component and an alkali or alkaline earth component with a porous carrier material, the composite containing, on an elemental basis, about 0.01 to about 2 wt. percent of the platinum group metal, about 0.01 to 5 wt. percent nickel, about 0.01 to about 5 wt. percent of the Group IVA metal and about 0.1 to about 5 wt. percent of the alkali metal or alkaline earth metal, the atomic ratio of nickel to platinum group metal being about 0.2:1 to about 20:1, the atomic ratio of the Group IVA metal to the platinum group metal being about 0.05:1 to about :1 and the atomic ratio of the alkali or alkaline earth metal to the platinum group metal being about 5:1 to about 50:1.

2. A method as defined in Claim 1 wherein the platinum group component is platinum or a compound of platinum.

3. A method as defined in Claim 1 wherein the platinum group component is palladium or a compound of palladium.

4. A method as defined in Claim 1 wherein the porous carrier material is refractory inorganic oxide.

5. A method as defined in Claim 4 wherein the refractory inorganic oxide is alumina.

6. A method as defined in Claim 1 wherein the alkali or alkaline earth component is a compound of lithium.

7. A method as defined in Claim 1 wherein the alkali or alkaline earth component is a compound of potassium.

8. A method as defined in Claim 1 wherein the Group IVA metallic component is germanium or a compound of germanium.

9. A method as defined in Claim 1 wherein the Group IVA metallic component is tin or a compound of tin.

10. A method as defined in Claim 1 wherein the Group IVA metallic component is lead or a compound of lead.

11. A method as defined in Claim 1 wherein the catalytic composite comprises a combination of eatalyticallyj effective amounts of a platinum component, a nickel com ponent, a germanium component, and an alkali or alkaline earth component with an alumina carrier material. a

12. A method as defined in Claim 11 wherein the composite contains on an elemental basis about 0.01 to about 2 wt. percent platinum, about 0.01 to about 5 wt. percent nickel, about 0.01 to about 5 wt. percent germanium and about 0.1 to about 5 wt. percent alkali or alkaline earth metal.

13. A method as defined in Claim 11 wherein the composite contains, on an elemental basis, about 0.05 to about 1 wt. percent platinum, about 0.05 to about 2 wt. percent nickel, about 0.05 to about 2 wt. percent germanium and about 0.25 to about 3.5 wt. percent alkali or alkaline earth,

metal.

14. A method as defined in Claim 11 wherein the alkali or alkaline earth component is a compound of lithium. 15. A method as defined in Claim 11 wherein the. alkali or alkaline earth metal is a compound of potassium.

16. A method as defined in Claim 11 wherein the atomic ratio of nickel to platinum is about 1:1 to about;

18. A method as defined in Claim 1 whereinthe dehydrogenatable hydrocarbon is an aliphatic compound containing 2. to 30 carbon atoms per molecule. w

19. A method as defined in Claim 1 wherein the de-. hydrogenatable hydrocarbon is a normal paraflin hydro carbon containing about 4 to 30 carbon atoms per mole-v cule.

20. A method as defined in Claim 1 wherein the .de-' hydrogenatable hydrocarbon is a normal parafiin hydrocarbon containing about 10 to about 18 carbon atoms per molecule.

21. A method as defined in Claim 1 wherein the dehydrogenatable hydrocarbon is an alkylaromatic, the alkyl group of which contains 2 to 6 carbon-atoms.

22. A method as defined in Claim 1 wherein the dehydrogenatable hydrocarbon isanaphthene. 1

23. A method as defined in Claim 17 wherein the dehydrogenation conditions include a temperature of about 700 to about 1200 F., a pressure of about 0.1 to about 10 atmospheres, a liquid hourly space velocity of about 1 to 40 hr. and a hydrogen to hydrocarbon mole ratio of about 1:1 to about 20:1. I

References Cited 7 UNITED STATES PATENTS 3,686,340 8/1972 Patrick et al'. 260-672 R 3,647,719 3/1972 Hayes et al. 252-466 PT- 3,094,493 6/1963 NiXOn 252 "4 66'B 

